Control devices



April 1963 M. J. CAPARONE ETAL 3,087,642

' CONTROL DEVICES 3 Sheets-Sheet 1 Filed Feb. 15, 19 60 Emmy 0.

April 30, 1963 M. J. CAPARONE ETAL 3,087,642

CONTROL DEVICES Filed Feb. 15, 1960 3 Sheets-Sheet 2 April 1963 M. J. CAPARONE ETAL 3,087,642

CONTROL DEVICES I 3 Sheets-Sheet 3 Filed Feb. 15, 1960 United States Patent 3,087,642 CONTROL DEVICES Michael J. Caparonc, Arcadia, and Theodore J. Dykzeul,

Rolling Hills, Calif, assignors to Robertshaw-Fulton Controls Company, Richmond, Va., a corporation of Delaware Filed Feb. 15, 1960, Ser. No. 8,692 9 Claims. (Cl. 220-31) This invention relates to control devices and more particularly to a cover assembly for a plurality of dials, knobs, and the like. 1

In most control installations, it is desirable to enclose all control adjustment or actuation devices that are seldom used, so that these devices will be less subject to unnecessary and unwarranted tampering. Additionally, the enclosure of the control adjustment or actuation devices should be a relatively inexpensive, durable and decorative enclosure which gives structural protection to the control while being easily detachable without the use of tools to expose the control for inspection. For control adjustment devices that are used infrequently, it is desirable that the cover assembly have a hinged portion concealing the devices in the closed position, whereas in the open position, the adjustment devices are easily accessible.

It is an object of this invention to enclose adjustment devices on a control or similar device by a cover assembly of functional and decorative design.

Another object of this invention is to enclose a control device by a cover assembly which has a hinged portion which can be readily opened to expose the adjustment means of the control.

Still another object of this invention is to facilitate assembly and disassembly of a cover assembly for a control device by movement of the cover relative to the control body.

A further object of this invention is to reduce the number of parts of a cover assembly enclosing a control device to a minimum so as to render the cover assembly economical to manufacture and install.

The above and other objects and features of the invention will appear more fully from a consideration of the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of the control cover assembly with the hinged member raised;

FIG. 2 is a front elevation view of the control cover;

FIG. 3 is a sectional view of the control cover taken along the lines III-III of FIG. 2;

. FIG. 4 is a top plan view of the control cover;

FIG. 5 is a top plan view of the hinged member of the control cover;

FIG. 6 is a front elevation view of the hinged member shown in FIG. 5;

FIG. 7 is a side elevation view of the hinged member shown in FIG. 5;

FIG. 8 is a sectional view of the hinged member taken along the lines VIII-VIII of FIG. 6; and

FIG. 9 is a bottom plan view of the hinged member shown in FIG. 5.

FIG. 10 is a view similar to FIG. 1 illustrating another embodiment of the invention.

Referring more particularly to FIG. 1, the invention is shown in connection with a control device 10, such as a water heater temperature and flame failure control, which has a substantially rectangular body or casing 12 having a plurality of control knobs 14 and 16 protruding from the top wall 18 and a temperature control knob 20 protruding from the front wall 22.

A portion of the front wall 22 and the sidewall 24 of 3,087,642 Patented Apr. 30, 1963 "ice the rectangular body is formed with recessed surfaces 26 and 28, respectively. Each recessed surface 26 and 28 terminates short of the base of the control device 10 to define an adjoining bottom shoulder 30 extending partially along the front and sides of the control device 10. A longitudinal shoulder 32 formed substantially at right angles to sidewall 24 and recessed surface 28 extends from top wall 18 to the upper surface of bottom shoulder 30.

A pair of spaced upper and lower wedge-shaped projections 34 and 36 are integrally formed on the surface of each sidewall '24 and project outwardly thereof. Projections 34 and 36 extend normally to the surface of longitudinal shoulder 32 and are centrally located relative to the width of recessed surface 28 and extend substantially the width thereof so that the ends of projections 34 and 36 are spaced from longitudinal shoulder 32 and front wall 22. The ends of projections 34 and 36 are formed as inclined surfaces so as to act as cammed surfaces for sliding members engaging the respective ends.

A circular surface is centrally located on the lower portion of control device It) and has a semicircular shoulder 38 separating the surface from recessed surface 26. Temperature control knob 20 is rotatably mounted on the circular surface. Spaced adjacent control knob 20 and located on recessed surface 26 is a pilot adjustment key 40 which operatively adjusts the pilot fluid flow through the control device 10.

Adjacent and parallel the edge formed by top wall 18 and sidewalls 24 of the body 12, there is located a pair of slots 42 in the top wall 18, as best illustrated in FIG. 10. Although not shown in FIG. 1, it will be understood that two additional slots or a single elongated slot extending the width of the top wall 18 will be formed in the top wall 18 adjacent to the edge formed by top wall 18 and the other sidewall 24 for purposes apparent hereinafter.

A cover 44, shown in FIGS. 2, 3, and 4, encloses substantially the front portion of body 12 and extends along each side thereof a distance equal to the width of recessed surface 28. Cover 44 is formed from a plastic or other flexible material and has a substantially U- shaped configuration in plan. A semicircular cutout 46 is formed in the front panel 48 and has a diameter sulficiently great to accept semicircular shoulder 38 on body 12. An indicating arrow, in the form of a raised boss '49, on the front of the cover serves as an indicator by which the control knob 20 can be positioned on assembly. Side panels 50 are integrally formed with front panel 48 of cover 44 and extend substantially at right angles thereto. The elongated length of side panels 50 substantially corresponds to the elongated length of recessed surface 28.

Molded integrally with the upper portion of front panel 48 and side panel 50 are outwardly extending flat arms 52. Arms 52, as shown in FIG. 4, are offset from side panels 50 so that the bottom edge of each arm. is spaced thereapart a distance corresponding to the distance separating the slots 42 on the top surface 18 of body 12. As shown in FIG. 3, at least one of the arms 52 has downwardly depending projections 54 located on its lower-most edge. Projections 54 are spaced from each other a distance equal to the spacing of slots 42.

Adjacent the rear edge 56 on the inner side of each side panel 50 and extending from substantially the lowermost vertical portion to the bottom edge of arm 52, there is located a wedge-shaped rib 58. Each rib 58 is constructed to have a sufficient width to extend between the space formed between one end of projections 34 and 36 and longitudinal shoulder 32. A small boss 60 is formed on each of the side panels 50 adjacent each rib 58 and projects inwardly of the plane of each side panel 50.

Each boss is positioned on side panel 50 a distance from the lowermost edge, which distance is slightly less than the distance of projection '34 on surface 28 from shoulder 30.

As best shown in FIGS. 2 to 4, the outer dimensions of the width of front panel 48 and side panels 50' are of substantially the same dimensions as the width of body 12 and the width of recessed surface 28, respectively. The length of the arms 52 extending from the front panel 48 to the rear edge corresponds to the horizontal dimension of the sidewall 24 of body 12.

In the assembled position of cover 44 to the body 12, the upper edge 62 of front panel 48 and upper edges 64 of arms 52 are spaced above the top surface 18 of body 12 to thereby enclose protruding control knobs 14 and 16 on three sides.

Adjacent the upper edge 62 of front panel 48 and arouately extending outwardly of :arms 52 in a horizontal direction is a flat Uashaped reinforcing rib 66. Centrally located in the bight portion of rib 66 is a rectangular aperture 68. The upper edge 64 of each arm 52 increases in height with the distance along arm 52 spaced from front panel 48. At the outer rear portion of each arm 52 there is located an outwardly extending cylindrical projection 70.

Thus, when cover 48 is in its assembled position on body 12, ribs 58 engage the rear portions of projections 34 and 36 to prevent outward movement of cover 44. Boss 60 engages the lower surface of projection 34 to prevent upward movement of cover 44. Projections 54, engaging slots 42 on the upper surface 18 of body 12, also prevent outward movement of cover 44; and, in addition, prevent lateral movement of each arm 52 relative to body 12. Therefore, any initial disassembly movement of cover 44 by an angular pull between the horizontal and vertical will be hindered by a combined action of ribs 58, projections 54, and bosses 60.

However, since cover 44 is constructed of a thin flexible material, such as plastic, assembly or disassembly of cover 44 to control device 10 can be accomplished by sliding the cover either vertically relative to top wall 18 or horizontally relative to front wall 22. In the vertical method, boss 60 will override projection 34 and ribs 58 will move vertically in the guide tracks formed by shoulder 32 and the ends of projections 34 and 36. Projections 54 on arms 52 will be vertically displaced relative to slots 42 located in top wall 18.

If, however, the control device 10 is positioned such that there is a limited free space above the control, the cover 44 can be assembled or disassembled by the horizontal method. For disassembly, the cover 44 is displaced a short distance vertically such that the lowermost surface of downwardly depending projections 54 are raised upwardly a sufiicient distance to be completely disengaged from slot '42. A force is then exerted in the horizontal direction outwardly of front wall 22 such that ribs 58 on side panels 50 override the ends of projections 34 and 36. The inclined ends of projections 34 and '36 aid the disassembly operation by causing a gradual flexing of cover 44, thereby allowing cover 44 to be completely removed from body 12. Cover 44 can be assembled by reversing the disassembly movements.

It will thus be readily apparent that cover 44 can be assembled and disassembled by any combination of the horizontal and vertical movements described whereby a plurality of angles and directional movements can be used.

However, since the cover 44 is constructed of a thin flexible material, such as plastic, disassembly is possible by upward movement of cover 44 whereby bosses 60 override projections 34 and projections 54 are no longer seated in slots 42. Flexure of cover 44 allows ribs 58 to become disengaged from and override wedge-shaped projections 34 and 36, thereby allowing cover 44 to be completely removed from body 12.

FIGS. to 9 illustrate a hinged top cover 72 that coopcrates with cover 44 to substantially enclose the top portion of control device 10. Top cover 72 is formed from a plastic or other flexible material and has a substantially rectangular configuration in plan, whose dimensions are approximately the same as the outer dimensions of cover 44 in plan. Top cover 72 has a crown portion 74 and a pair of depending side members 76. In the assembled position to cover 44, side members 76 are designed to conceal side arms 52 and partially conceal the upper portions of side panels 50. A plurality of reinforcing ribs 78 are integrally formed with the underside of crown portion 74 to [form a rigid construction whereby top cover '72 can be handled without damage when assembling and disassembling to cover 44.

A rectangular ribbed tab 80, which has a small wedgeshaped detent 82 formed thereon, is located adjacent the front edge of top cover 72 at the center of the lower surface of crown portion 74. Also depending from the lower surface of crown portion 74 and located substantially intermediate the front and rear edges is a downwardly depending V-shaped member 84. As will later become apparent, member 84 is positioned relative to cover 44 and the upper surface 18 of body 12 so that when top cover 72 is in its operative closed position with cover 44, rnember 84 is positioned over the center of control knob 16 with a free space between the lowermost portion of member 84 and the upper surface of control knob 16.

Adjacent each rear edge 86 of side member 76 of top cover 72 are two ribbed members 88 forming an elongated tapered slot 90 therebetween. Intermediate the length of slot 90, an inclined slide 92 is integrally formed and connects the lower surface of slot 90 to an intermediate surface 94 which is bounded by portions of the two ribbed members 88 and the bight portion connecting them. Surface 94 is located slightly below the upper edge of each ribbed member 88. Centrally located in surface 94 is a circular recess 96 which has a sutiable diameter for accepting circular projections 70 of cover 44.

Closely adjacent to each recess 96 but spaced a distance therefrom which is slightly greater than the thickness of arm 52 is a downwardly depending flexible tab 98. Tab 98 is integrally formed with top cover 72.

Top cover 72 is secured to cover 44 by inserting each projection 70 of cover 44 into corresponding slot 90 of top cover 72. Upon movement of top cover 72 towards cover 44, projections 70 ride in slot 90 and up inclined slide 92. The outer ends of projections 70 rest on surface 94 adjacent recesses 96. The upper surface of arms 52 engage a portion of the lower surface of tabs 98. Further movement of cover 44 into engagement with top cover 72 bends flexible tabs 98 to allow projections 70 to drop into recesses 96. It is to be noted that both cover 44 and top cover 72 are constructed of a flexible plastic material so as to allow some flexure of both members. An appreciable effort is required to separate cover 44 and top cover 72 to thus prevent separation of the hinged joint in ordinary operation.

As best shown in FIG. 1, when top cover 72 is rotatably mounted to cover 44, tab 80 will be inserted through aperture 68 in reinforcing rib 66. Detent 82 located on tab 80 will engage the edge of the bottom opening of aperture 66 to securely latch top cover 72 to cover 44.

There is shown in FIG. 10 another embodiment for latching top cover 72 to cover 44, wherein tab 80 and aperture 68 can be eliminated. A projection 100 is integrally formed on each arm 52 and extends outwardly thereof. The length of projection 100 is suflicient so that the top of projection 100 engages ribs 88 located on the sidewalls 76 of top cover 72. Projections 100 are so positioned on arms 52 as to engage the side surfaces of ribs 88 to act as a latching mechanism when the top cover 72 is in the closed position with cover 44.

Upon pressure being exerted adjacent the top of top cover 72 in its closed position, the cover will flex downwardly and the projection 84 will contact the top of control knob 16, providing added support to prevent excessive bending or breakage of the top cover 72. Thus, it will be seen that cover 44 and top cover 72 cooperate in their closed mounted position to protect the control device from any accidental damage.

It will also be readily understood that opening of top cover 72 allows access to control knobs 14 and 16 without requiring removal of the entire cover assembly. In addition, the cover assembly can easily be removed to adjust pilot adjustment key 40, but normally this adjustment is made at the time of the initial installation and need not be made again.

Since the hinged top cover has great versatility in its assembly and disassembly movement, it can be employed in a great variety of installations where free space above or in front of the control device is limited. For example, in some water heater installations where the thermostatic control is recessed in a door compartment, it would be a distinct advantage to use .a horizontal assembly and disassembly operation so as to avoid interference with the walls of the compartment.

It is to be understood that although two embodiments and modifications of this invention have been shown and described for purposes of illustration, the invention can be variously embodied and changes can be made in the construction and arrangement of parts without departing from the scope of the invention as defined by the appended claims.

We claim:

1. In combination: a casing comprising a body membet, a removable front cover for said body member, and a top cover for said body member, said body member having a vertical rectangular rear wall with vertical side edges, a substantially rectangular side wall of a substantially lesser height than said body member rear wall attached to each of said body member rear wall side edges and projecting perpendicularly forwardly from such rear Wall with its lower end in the same horizontal plane as the bottom of the rear wall and a narrow horizontally elongated vertical front wall secured to the front edges of the side walls with its lower edge in the same plane as the plane defined by the bottom edges of the aforementioned rear and side Walls, the top edge of the front wall being spaced from the top edges of the said side walls a major portion of the distance from the top to the bottom of the side wall, said side walls each being provided at its front with an outwardly opening rabbet, said front cover comprising a substantially rectangular vertical wall of the same horizontal width as the body member rear wall and having a height substantially equal to the difference in heights of the body member front and rear walls, a rectangular side Wall of the same height as the cover front wall attached to each vertical edge of said front Wall and projecting perpendicularly rearwardly therefrom with its top and bottom edges lying in the same planes as the top and bottom edges respectively of said front wall, a rearwardly extending rectangular vertical plate-like arm extending from each cover side wall adjacent its top, such arm being of the same horizontal length as the horizontal length of the body member side Walls, and having an outwardly extending cylindrical projection located at the upper rear end thereof, and said top cover comprising a substantially rectangular crown portion having a pair of depending side members oppositely equal to the combined thickness of said side walls greater than the spaced distance of said side walls and each of said side members having two downwardly tapering rib members adjacent the rear edge of each of said side members extending downwardly and divergently from said crown portion to form an elongated and tapered slot therebetween with an integrally formed outwardly inclined gradually increasing thickening of the material included between said tapering rib members from a point substantially intermediate the length of said slot to form an inclined slide having a centrally located circular recess formed in the top terminal thereof adjacent the lower surface of said top cover for receiving a respective one of said outwardly extending cylindrical projections.

2. In combination, a casing for a control device having a substantially rectangular body member, a removable front cover for said body member, and a top cover for said body member, said body member having vertical oppositely disposed side wall portions with a lateral projection and a forwardly facing shoulder on each, said body member having a top wall portion with a plurality of upwardly extending protuberances thereon, said front cover having a front panel covering the front of said body member, side panels extending rearwardly from said front panel and covering part of said side wall portions of said body member, a pair of arms extending rearwardly form the top portions of said side panels, an interiorly formed rib extending along the rear edge of each of said side panels and receivable between a respective one of said shoulders and said projections on one of said side wall portions of said body member to detachable secure said front cover to said body member, and said top cover having a generally horizontally extending top wall covering the top wall portion of said body member, side wall members depending from said top cover, means on said top cover for rotatably and detachably mounting said side wall members of said top cover on said arms to form a chamber to accept said protuberances on said body member when said top cover and said front cover are in closed position, and means formed on the top inner surface of said top cover to engage at least one of said protuberances when said top. cover is flexibly distorted.

3. In combination: a casing comprising a substantially rectangular body member, a removable front cover for said body member and a removable top cover for said body member, said body member having vertical oppositely disposed side wall portions, said body member having a front wall portion and a top wall portion, said front cover having a front wall panel covering said front wall portion of said body member, a pair of side wall panels extending rearwardly from said front wall panel and covering part of said side Wall portions of said body member, a pair of arms extending rearwardly from said side wall panels for retention by resilient compression thereof about said front wall and said side wall portions of said body member, said arms having projections formed on intermediate portions thereof and extending outwardly from the sides thereof, and said top cover having downwardly extending side members to cooperate with said arms of said side cover to form a closure therewith for enclosing said top wall portion of said body member, said top cover having hinge means operatively connecting each of said downwardly extending side walls of said top cover to a respective one of said arms for pivotally mounting said top cover for concealing said top wall portion of said body member when said top cover is in its closed position, and inwardly projecting substantially horizontal ribs formed on each inner side wall of said top cover adjacent the rear end thereof defining a slot intermediate said ribs to override a respective one of said projections on said arms and latch said top cover in its closed position for enclosing substantially all the top and front surfaces of said body member of said control casing.

4. In combination: a casing comprising a substantially rectangular body member, a removable front cover for said body member, and a top cover for said body member, said body member having vertical opposite recessed side wall portions, each of said recessed portions being formed with a longitudinal and forwardly facing shoulder and a lateral projection spaced from said shoulder, said front cover comprising a hollow shell of thin flexible material with a front panel covering the front portion of said body member, a pair of side panels projecting rearwardly from said front panel and covering part of said side wall portions of said body member, a pair of arms extending backwardly from the rear of said side panels, each side panel having a continuous longitudinal and vertical rib adjacent the marginal edge thereof and facing inwardly, each of said ribs extending into the space between a related one of said projections and a related one of said adjacent longitudinal shoulders, said front cover receiving a projection between each said rib and said front panel for retaining said cover in position from which said cover is detachable by flexing, a pair of pivot constructions on said arms, and said top cover being interconnected to said pivot constructions on said arms by flexing, said top cover pivotally movable between open and closed positions about said pivot constructions and forming an end closure for the top of said body member with said front cover when said top cover and said front cover are in the closed positions thereof.

5. In combination, a casing for a control device comprising a substantially rectangular body member, a removable front cover for said body member, and a top cover for said body member, said body member having a top wall, upwardly extending adjustment controls located on said top wall, said body member having vertical side walls, a pair of recesses formed in said side walls and having longitudinal and vertical forwardly facing shoulders, a pair of spaced lateral projections on each of said recesses extending outwardly of said longitudinal shoulders substantially the width of said recesses, said top wall of said body member having downwardly extending slots adjacent each top edge of its said sides, said front cover being formed of thin flexible material and having a front panel covering the front of said body member, said front cover having a pair of rearwardly directed side panels covering part of said side walls of said body member, said side panels having a pair of arms formed on the upper portion of said side panels and extending rearwardly therefrom, lugged projections on each lower edge of said arms for extension into said slots, longitudinal and vertical ribs located adjacent the marginal edges of side panels for engagement between the inner-most lateral edges of said spaced lateral projections and said longitudinal shoulders to tend to prevent removal of said cover from said casing, said top cover being pivotally and detachably mounted on said arms, said top cover being of a size and shape to cooperate when closed with said front cover to substantially enclose top portions of said body member whereon said adjustment controls are mounted and to provide access to said adjustment controls when opened.

6. In combination: a casing comprising a substantially rectangular body member, a removable front cover for said body member, and a top cover, said body member having a vertical back wall and a vertical front wall, said body member having a top wall and oppositely disposed vertical side wall portions, each of said side wall portions being provided with a recessed surface defining a longitudinal and vertical forwardly facing shoulder, a lateral projection on each recessed surface, said front cover having a front panel and covering the front of said body member, a pair of rearwardly directed side panels covering part of said side wall portions of said body member, an arm on the upper portion of each of said side panels and extending rearwardly therefrom, vertically disposed rib means on each inner surface of said side panels for engagement between one of said longitudinal shoulders and one of said projections in said recessed surface to retain said front cover in position, a latch keeper on the upper edge of said front panel of said front cover, said top cover having downwardly extending side members, hinge means carried by said top cover and said front cover for pivotally and detachably connecting said top cover to said arms, a resilient latch member formed on said top cover in alignment with said latch keeper on said front panel of said front cover to retain said top cover in engagement with said front cover to provide a latched end closure for the enclosed top portion of said body member.

7. The construction as defined in claim 6 wherein said hinge means includes an outwardly extending projection on the outer side surfaces of the remote portion of said arms, and a recess in the inner side surfaces of each of said downwardly extending side members of said top cover, said projections being rotatably mounted in said recess.

8. The construction as defined in claim 7 wherein said hinge means further includes a downwardly projecting tab integrally formed with said top cover adjacent each said recess on the inner side surfaces of said side panels and being spaced from said recesses a distance less than the distance from the inner wall of said arms to the remote ends of said projections to thereby tend to prevent said projections from being disengaged from said recesses.

9. The construction defined in claim 8 with further inclusion of a pair of inwardly directed and substantially horizontal rib members on each inner side wall of said top cover to form a slot therebetween, said top cover having fiat surface means forming a flat surface located in said slot, said recess being centrally located in said fiat surface and the inner surface of said side wall between said pair of ribs, said slot accepting said projection so movement of said projection in said slot along said tab and said fiat surface and flexure of said top cover causes said projection to be received in said recess.

References Cited in the file of this patent UNITED STATES PATENTS 2,250,977 Walker July 29, 1941 2,330,975 Jackson Oct. 5, 1943 2,605,926 Casey Aug. 5, 1952 2,656,948 McGee Oct. 27, 1953 2,680,533 Cole June 8, 1954 2,735,542. Shnitzler Feb. 21, 1956 2,765,949 Hillman Oct. 9, 1956 2,796,190 Tupper June 18, 1957 2,867,348 Morrison Jan. 6, 1959 

1. IN COMBINATION: A CASING COMPRISING A BODY MEMBER, A REMOVABLE FRONT COVER FOR SAID BODY MEMBER, AND A TOP COVER FOR SAID BODY MEMBER, SAID BODY MEMBER HAVING A VERTICAL RECTANGULAR REAR WALL WITH VERTICAL SIDE EDGES, A SUBSTANTIALLY RECTANGULAR SIDE WALL OF A SUBSTANTIALLY LESSER HEIGHT THAN SAID BODY MEMBER REAR WALL ATTACHED TO EACH OF SAID BODY MEMBER REAR WALL SIDE EDGES AND PROJECTING PERPENDICULARLY FORWARDLY FROM SUCH REAR WALL WITH ITS LOWER END IN THE SAME HORIZONTAL PLANE AS THE BOTTOM OF THE REAR WALL AND A NARROW HORIZONTALLY ELONGATED VERTICAL FRONT WALL SECURED TO THE FRONT EDGES OF THE SIDE WALLS WITH ITS LOWER EDGE IN THE SAME PLANE AS THE PLANE DEFINED BY THE BOTTOM EDGES OF THE AFOREMENTIONED REAR AND SIDE WALLS, THE TOP EDGE OF THE FRONT WALL BEING SPACED FROM THE TOP EDGES OF THE SAID SIDE WALLS A MAJOR PORTION OF THE DISTANCE FROM THE TOP TO THE BOTTOM OF THE SIDE WALL, SAID SIDE WALLS EACH BEING PROVIDED AT ITS FRONT WITH AN OUTWARDLY OPENING RABBET, SAID FRONT COVER COMPRISING A SUBSTANTIALLY RECTANGULAR VERTICAL WALL OF THE SAME HORIZONTAL WIDTH AS THE BODY MEMBER REAR WALL AND HAVING A HEIGHT SUBSTANTIALLY EQUAL TO THE DIFFERENCE IN HEIGHTS OF THE BODY MEMBER FRONT AND REAR WALLS, A RECTANGULAR SIDE WALL OF THE SAME HEIGHT AS THE COVER FRONT WALL ATTACHED TO EACH VERTICAL EDGE OF SAID FRONT WALL AND PROJECTING PERPENDICULARLY REARWARDLY THEREFROM WITH ITS TOP AND BOTTOM EDGES LYING IN THE SAME PLANES AS THE TOP AND BOTTOM EDGES RESPECTIVELY OF SAID FRONT WALL, A REARWARDLY EXTENDING RECTANGULAR VERTICAL PLATE-LIKE ARM EXTENDING FROM EACH COVER SIDE WALL ADJACENT ITS TOP, SUCH ARM BEING OF THE SAME HORIZONTAL LENGTH AS THE HORIZONTAL LENGTH OF THE BODY MEMBER SIDE WALLS, AND HAVING AN OUTWARDLY EXTENDING CYLINDRICAL PROJECTION LOCATED AT THE UPPER REAR END THERE- 